And I'm Audie Cornish. The supply of nonlethal U.S. aid to opposition groups in Syria was suspended this week. That's after Islamist forces raided a warehouse where some of the aid had been stored. The supplies were meant for the U.S. backed Supreme Military Council, but the moderate rebel group has largely been sidelined by more radical elements. NPR's Tom Gjelten reports the U.S. government may now have to work with some rebel groups it has previous avoided.

TOM GJELTEN, BYLINE: The supply seized last Friday in northern Syria, about $1 million worth, including pickup trucks, passenger buses and communication equipment, were supposed to go to forces allied with General Salim Idris, the main U.S. contact in the Syrian opposition. But General Idris' forces haven't been doing so well lately in the fight in the north against the Syrian regime. The initiative, instead, is with rebel groups making up the so-called Islamic Front.

It was apparently those groups that took the supplies meant for Gen. Idris. Valerie Szybala, a Syria analyst at the Institute for the Study of War, thinks Idris' days as a rebel leader may now be numbered.

VALERIE SZYBALA: Idris is severely weakened. It's not clear that his coalition is going to be able to survive, even in name, with these latest blows to their legitimacy on the ground.

GJELTEN: Idris leads the Supreme Military Council, but the council isn't a fighting force as much as it is an organization set up to receive Western aid. And Szybala says, Idris and his fellow officers didn't do a great job, even at that.

SZYBALA: They were never effective at coordinating deliveries of supplies and equipment to forces that needed it, which limited their ability to command those forces. But at this point, they may cease to exist altogether.

GJELTEN: Some of the brigades that had been part of the Supreme Military Council have since joined the Islamic Front. The Front is a wide alliance of groups, some radical, some pragmatic, but all sharing Islamist ideas. Until now, the United States has avoided the Islamist groups, preferring secular forces instead. That's been a key dividing line. But going forward, the Obama administration may need to work with a wider range of rebel groups.

Andrew Tabler of the Washington Institute for Near East Policy says the new dividing line may be between those rebel forces allied with al-Qaida jihadists across the Middle East and those who simply want an Islamic state inside Syria. That's the position of most groups in the Islamic Front.

ANDREW TABLER: They don't really have aspirations beyond Syria's borders. Jihadists, on the other hand, they have political aspirations beyond Syria and they would like to not only set up an Islamic state, but they will use extreme measures, including suicide bombs and other kinds of terrorists methods, to set that up.

GJELTEN: Speaking today in Jerusalem, Secretary of State John Kerry said the United States still as confidence in General Idris, but Fred Hoff - until last year, President Obama's special advisor for Syria - says it's the Islamist elements in Syria who may now be key.

FRED HOFF: This is where the center of gravity has moved in the armed opposition and I think that there is really no alternative but for the administration to be in contact with those elements.

GJELTEN: And U.S. officials are already in contact with them. A senior administration official tells NPR it's logical to move forward in this regard because you can't just deal with secularists. Hoff, now at the Atlantic Council, says the next question is whether the United States can get some of the Islamist groups to join a conference about Syria's future planned next month in Switzerland.

HOFF: It's going to have to try to convince them to play a positive and creative role, either at the conference itself or in support.

GJELTEN: But Aaron Lund, who edits the Syria in Crisis website, says the United States may not want to insist that a group take part in a conference as a condition of U.S. support.

AARON LUND: If that was the demand, I think you'd limit yourself to a very small portion of the insurgency. What the United States has been trying to achieve, really, is to get these groups in the Islamic Front and similar factions to, you know, at least not oppose meeting.

GJELTEN: Just to keep quiet, Lund says, and not get in the way of any opposition element willing to participate. Lower and lower expectations for Syria, further and further from what the United States originally hoped for. Tom Gjelten, NPR News, Washington. Transcript provided by NPR, Copyright NPR.